a. Field of the Invention
This invention relates to a device and a method for extracting energy from surface waves in a body of water, for example, the sea.
b. Related Art
Deep water wave power resources are truly enormous. It has been estimated that The UK has an estimated recoverable resource of between 50-90 TWh of electricity a year; this is roughly 15-25% of the current UK electricity demand. Worldwide, the useful worldwide resource has been estimated to be greater than 8700 TWh per year.
One type of wave energy device is disclosed in patent document WO 2007/088325 A1. This relates to a distensible tube wave energy converter, formed from an elongate distensible tubular body which has an elastic outer wall entrains a bulge wave generated by wave passing over the device. Large storm waves pose a challenge to wave power development. Because the wave energy power take off is at one or both ends, the bulge wave energy at the take off will increase as the wave amplitude increases. This presents a problem in that the device may be over-stressed in very high seas.
It is an object of the invention to provide a wave energy device that deals with this issue.